Nakanoyu / Tsuchiyu Onsen (中の湯 / 土湯温泉)

Introduction: The Architectural Rebirth of a Legend in the Valley of Kokeshi

Nestled in the dramatic Arakawa River gorge, Nakanoyu (中の湯) is the beating heart of Tsuchiyu Onsen—one of Japan’s most resilient and forward-thinking hot spring communities. While Nakanoyu began as a modest concrete bathhouse for locals, its total reconstruction in 2018 has transformed it into a stunning symbol of modern Japanese woodcraft and universal design. This facility serves as the gateway to “Okutsuchiyu” (Deep Tsuchiyu), where the air is heavy with the scent of wild azaleas and the rhythmic sound of waterfalls. For the international traveler, Nakanoyu offers a bridge between high-tech sustainability—the town is a national leader in geothermal binary power—and ancient folklore. According to legend, these waters were discovered by the messenger of Prince Shotoku over 1,400 years ago. Today, you can soak in the same “Spirit Waters” that once healed poets and samurai, now housed in a barrier-free sanctuary that frames the seasonal shifts of the Fukushima highlands.

Key Information Table

The Healing Waters: The “Tsuru-Tsuru” Science of Two Sources

Nakanoyu is geologically unique because it provides access to two distinct mineral profiles within a single building.

1. The Simple Thermal Spring (Low Tension): Found in the large indoor tubs and the outdoor Rotenburo, this water is exceptionally gentle. From a balneological perspective, it is ideal for “acclimatization”—the first stage of a long hot-spring cure. It helps lower blood pressure and eases mental fatigue without the harsh mineral shock of acidic springs.

2. The Sodium-Bicarbonate Spring (“Beauty Water”): This water is funneled into the “Atsu-yu” (Hot Bath) and the private rental rooms. Bicarbonate ions act as a natural alkali surfactant, softening the skin’s outer layer and emulsifying surface oils. Bathers often report a “Tsuru-Tsuru” (slippery) sensation during the bath and a refreshing, silky finish afterward. Nakanoyu uses a 100% natural free-flowing (kakenagashi) system, blending three different underground sources to maintain a constant temperature of roughly 42-45°C in the hot pools.

Top 5 Recommended Stays in Tsuchiyu Onsen

• Hotel Sansuiso (水織音の宿 山水荘): A premier luxury resort overlooking a massive two-tier waterfall. Famous for its multi-story bathing complex and high-end kaiseki dining. It is the definitive choice for those seeking a grand Japanese experience.
• YUMORI Onsen Hostel: A creative reimagining of a traditional inn. It offers both dormitory beds and stylish private rooms, catering to backpackers and digital nomads. They feature a unique “Kokeshi Lounge” and English-speaking staff.
• Tsuchiyu Bettei Satonoyu (土湯別邸 里の湯): A secluded, high-end retreat with only a few rooms, each with its own cypress wood bath. Perfect for couples seeking ultimate privacy and deep forest views.
• Harumiya Ryokan (はるみや旅館): A traditional inn set directly along the mountain stream, known for its warm hospitality and private outdoor baths in every room.
• Gensenyuan Moriyama (源泉湯庵 蓮): Famous for its focus on the “purity of the source” and its innovative culinary approach using locally harvested mountain vegetables.

Must-Visit Neighborhood Spots: Kokeshi and Craters

The Kokeshi Workshop Trail: Tsuchiyu is one of Japan’s three major homes of the **Kokeshi Doll**. Walk the main street to see craftsmen hand-carving these limbless wooden icons. Don’t miss the 3-meter tall “Kokeshi Siblings” guarding the bridge—the town’s most iconic photo spot.

Arakawa River Walk: A scenic trail with several free footbaths (ashiyu) like “Kibokko-no-yu” where you can soak your feet while watching the mountain stream.

Tsuchiyu Pass & Bandai-Azuma Skyline: A 15-minute drive up the mountain leads to the “Volcanic Frontier,” featuring the moon-like landscape of Mt. Azuma-Kofuji and its perfectly circular crater.

Local Gastronomy: Giant Prawns and Vegan Buddha Bowls

Tsuchiyu has turned its geothermal energy into a culinary asset.
Giant Freshwater Prawns (Onitenaga-ebi): These tropical prawns are raised in the warm runoff water from the binary power plant. You can catch them yourself and have them grilled at the **Ebitsuri (Prawn Fishing) Cafe**.

Vegetarian/Vegan Survival:
Tsuchiyu Cafe & Crafts Lotus: A sanctuary for plant-based travelers. They serve specialized **Buddha Bowls** (reservation required 3 days prior) featuring seasonal mountain vegetables, teriyaki kurumafu (wheat gluten), and fermented local miso. Their **Vegan Banh Mi** uses soy-based smoked ham and is highly satisfying.
Sora Cafe: Located in a 100-year-old renovated farmhouse in the forest, offering “Yuru-Macrobiotic” (gentle macrobiotic) plates and vegan open sandwiches.

Cultural & Historical Context

The name “Tsuchiyu” is believed to derive from Tsuki-yu (Punched Water), referring to the legend of the deity Onamuchi-no-mikoto who supposedly created the spring by striking the earth with a spear. Historically, the town was a vital stop for pilgrims and travelers crossing the mountains. The **Kokeshi culture** evolved during the Edo period when woodworkers began making dolls as toys for the children of “Toji” (healing cure) guests. This fusion of craft and thermal wellness remains the soul of the community today.

Practical Travel Tips for International Visitors

• Tattoo Policy: Nakanoyu and Yumori Hostel are very tattoo-friendly. Public baths may still have traditional signs, but private rental baths (kashikiri-buro) at Nakanoyu are available for 1,500 JPY, providing a 100% stress-free experience for travelers with large pieces.
• Connectivity: Wi-Fi is excellent at the tourism center and modern hostels. However, smaller shops are strictly cash-only. Use the ATM at the 7-Eleven on the way to the village.
• Sustainability: Tsuchiyu is a “Model SDGs City.” Your visit supports renewable energy projects that provide free bus passes to local elderly residents.

2025-2026 Latest Updates

In 2025, Tsuchiyu launched the “Zero-Emission Onsen Tour,” which includes a visit to the binary power plant followed by a soak at Nakanoyu. For the 2026 season, new “Star-Viewing Decks” are being completed along the Arakawa riverbank for night-time meditation.

Safety & Manners

Bathing Manners: Nakanoyu does not provide soap or shampoo in the standard price (they are for sale at the desk). Always wash your body thoroughly before entering the tub.

Winter Safety: The road to Tsuchiyu remains open in winter, but snow tires are mandatory from December to April. Beware of “Black Ice” on the bridges over the Arakawa River.